I'm following the helloworld tutorial for RoboMaker, and when I have to launch the simulation application with the following command:
docker run -it -v /tmp/.X11-unix/:/tmp/.X11-unix/ -u robomaker -e ROBOMAKER_GAZEBO_MASTER_URI=http://localhost:5555 -e ROBOMAKER_ROS_MASTER_URI=http://localhost:11311 \robomaker-helloworld-sim-app:latest roslaunch hello_world_simulation empty_world.launch
it runs the application but it doesn't open Gazebo to visualize the robot, since I obtain the following problem
[Err] [RenderEngine.cc:725] Can't open display:
What could be the cause of this failure?